1. Field of the Invention
The present invention relates to a garment or garments incorporating a functional electrical or electronic circuit. Preferably, the invention relates to the incorporation into a garment of a breathable, porous, flexible fabric circuit for use as a heater. The garment may include a thermally activated chemical delivery system. The circuit may be used as an electrical interconnect (electro-conductive) system with or without electronic devices, e.g. as a keypad or keyboard.
2. Related Art
A primary function of garments designed for outdoor sports and leisure activities such as mountaineering, hiking, potholing, motorcycling, etc., is thermal protection, particularly from cold weather conditions. Similarly, such thermal protection is important in many work-wear applications (e.g. seamen, workmen, delivery personnel, refrigeration plant operators, airport workers, etc.) where, potentially, staff may be exposed to cold conditions for prolonged periods. Conventionally, protection from the cold has been achieved by incorporating within garments low-convection fabric structures capable of entrapping still air to provide thermal insulation (e.g. waddings or battings). The thermal insulation achieved by such structures is principally a function of fabric thickness: the insulation increases with fabric thickness. Therefore, existing garments with high thermal insulation can be thick and bulky and may have limited conformability. This can restrict the mobility and comfort of the wearer in use, which is disadvantageous.
The designs of various active heating systems capable of evolving heat in response to an energy input are known. These systems involve incorporating materials into fibres or films, coatings and laminated structures and specify the use of (for example); phase change materials, metals and exothermic materials. The incorporation of electrical heating systems within garments has also been described in the prior art and include continuous metallised fabric (GB-A-2092868), woven carbonised filament (U.S. Pat. No. 6,172,344 and GB-A-2336514) and insulated conductive yarn (U.S. Pat. No. 6,501,055) heating elements.